The present invention relates to a transmission drive unit with a zero backlash bearing fastening, in particular for adjusting a movable part in a motor vehicle.
Publication DE 198 545 35 A1 makes known a drive device for a windshield wiping system of a motor vehicle, which includes a housing and an armature shaft with a worm rotatably supported therein. Using an axial force-generating device, a sliding wedge element is displaced radially to the armature shaft in order to compensate for the axial play of the armature shaft. The displacement force of the sliding wedge element is applied by a preloaded spring element that presses the sliding wedge element radially against a stop of the armature shaft, thereby displacing the armature shaft axially until the axial play is compensated for. When a strong load is placed on the armature shaft by a driven wheel, an axial force is produced, via which the armature shaft is pressed against the sliding wedge element. The sliding wedge element is pressed back radially away from the armature shaft against the spring element. As a result of this strong, sustained load on the spring element, its service life, i.e., its elastic properties, is/are reduced, and the axial play of the armature shaft is therefore no longer compensated for. The armature shaft therefore moves back and forth axially when loaded, which can result in unpleasant “clacking” sounds being produced. Nor is a sliding wedge element of this type suited for the backlash-free axial support of a drive element in a largely closed support tube that does not have a cover and that is installed radially to the bearing axis.